Note: Descriptions are shown in the official language in which they were submitted.
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1452
POLYMER COMPOSITION
Background of the Invention
This invention relates to a composition of
polyoxyalkylene polymers and more particularly to polyoxy-
alkylene compositions as mold release agents or lubricants
in molding processes.
In the molding of natural and synthetic rubber and
certain other polymers, generally an efficient mold release
agent or lubricant is required to overcome the tendency of
the polymer to stick to the mold which is often of metal.
Both high temperatures and high molding pressures are often
encountered ln such molding processes~ To facilitate the
removal of the molded objects, lubricants of the prior art
have generally included mineral waxes, vegetable waxes,
~; fatty acids, and meta11lc soaps which are applied by spray
or other methods o coating to the mold surface.
It is also known to use polyoxyalkylene compounds
such as block and heteric copolymers of ethylene oxide and
propylene oxide for this purpose. An important application
is Eor use as a lubricant in the production of tires and
rubber hose. In the lattex case it is used as a lubricant
to allow easy removal of radiator-type hose from the
mandrels used to form the hose during vulcanization. A
preferred material for such application-is ~enerally
~ referred to as EPDM.
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The term "EPDM" is used in the sense of its
definition as found in ASTM-D-1418-64 and is intended to
mean a terpolymer of e-thylene, propylene and a diene
monomer. Illustrative methods for preparing such terpoly-
mers are found in U.S. Pat. No. 3,280,082 and British Patent
No. 1,030,289. The preferred terpolymers contain from about
40 to about 80 weight percent ethylene and from about 1 to
about 10 weight percent of the diene with the balance of -the
terpolymer being propylene. This is an elastomer which can
be vulcanized; used for automotive parts, cable coating,
hose, footwear, and other products. The copolymers employed
in the prior art as mold release agents present problems in
that they do not give complete wetting on the EPDM elastomer
surface and tend to solidify and flake off after vulcaniza-
tion, thus giving a non-uniform appearance which is found
objectionable by customers for these products. ~t is
desirable for such products to give good wetting both before
and after vulcanization. Also, the rubber products should
have a matte finish, i.e., be free from shine or at least
from a high shine and the mold release composition should
give complete wetting both at room temperature and 45C.
U.S. Patent 4,217,394 discloses mold release com-
positions suitable for lubricating metal molds employing
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polyoxyalkylene compounds and including mixtures of ~ore
than one polyoxyalkylene compound~ Howe!ver an essential
compound of the lubricant in question includes in its
structure a phenolic residue.
Summary of the Invention
The instant invention relates to a rubber lubri-
cant composition characterized by complete wetting oE the
elastomer surface both before and after vulcani2ation which
gives a matte finish on cooling down that remains soft and
does not flake off. This comprises (1) polyoxypropylene
polyoxyethylene block copolymer having a molecular weight
of the polyoxypropylene hydrophobe of about 2500 to 4000 and
containing 20 to 80 percent oxyethylene groups and t2) an
oxyethylated oxypropylated higher alcohol,
Description of the Preferred Embodiments
The polyoxyethylene-polyoxypropylene block
copolymer of use in the invention is a cogeneric mixture of
conjugated polyoxyethylene-polyoxypropylene compounds
corresponding to the following formula:
E~o(C2H~O)m(C3H6O)n(C2H4 )m
.
wherein n has a value such that the molecular weight of the
polyoxypropylene hydrophobe baæe is about 2500 to 4000 and m
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represents from about 20 to 80 weight percent of the
molecule~ The oxypropylene chains optionally, but advanta-
geously, contain small amounts of oxyethylene and oxybuty-
lene groups and the oxyethylene chains also optionally, but
advantageously, contain small amounts of oxypropylene and
oxybutylene groups. These compositions are more parti-
cularly described including the method of preparation in
U. S~ Patent Nos. 2~677,700 and 2,674,619.
The second component of the composi-tion of the
instant invention is prepared by the condensation of an
essentially linear primary aliphatic alcohol having from 10
to 18 carbon atoms in the aliphatic chain, or, preferably, a
mixture of such alcohols with a critical amount oE a mixture
of ethylene oxide and propylene oxideO The products of the
present invention are the products obtained by condensing,
on a weight basis, 20 percent to 45 percent alcohol, 30
percent to 55 percent propylene oxide, and 20 percent to 3S
percent ethylene oxide. These products are a cogeneric
mixture of compounds represented by the following formula:
R-O(A)H II
: wherein:
: R is an essentially linear alkyl group having from
10 to 18 carbon atoms, with the proviso that at least 70
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weight percent of said compounds in saidl mixture have an R
of from 12 to 16 carbon atoms, and
A is a mixture of oxypropylene and oxyethylene
groups, said oxypropylene and oxyethylene groups being from
55 percent to 80 percent of the total weight of the com-
pounds, the oxypropylene to oxyethylene ratio of said total
weight being from 0.85:1 to 2.75:1. The R-O in the fore-
going formula may also be defined as the residue of the
alcohol or alcohol mixture employed in the condensation
reaction, i.e., the alcohol or alcohol mixture with the
hydrogen of the OH radical removed. rrhese compositions are
more particularly described, including the method of
preparation, in U.S. Patent No~ 3,504,041.
The term "cogeneric mixture," as used herein,
designates a series of closely related homologues that are
obtained by condens~ng a plurality of oxide units with an
alcohol or a mixture thereof. (See U. S. Patent No.
2,549,438, particularly column 2, line 40 et seq.) As is
known, when a mixture oE compounds of this type is gener-
; ated, various oxyalkylene chain lengths are obtained.
Accordingly, throughout this application when oxyalkylene
wei~ht percents are referred to,-average weight percents are
meant.
The composition of the instant invention contains
from about 80.0 to 99.5 percent by weight oE the compound of
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formula I, above, and about 20 to 0.5 Fercent by weight of
the compound of formula II, above. In the process oE
lubricating a metal mold, the polyoxyalkylene compounds of
the instant invention are applied as a two-component blend
and coated onto the metal mold or mandrel, preferably by
sprayingS
While the mold release composition of the inven-
tion is particularly suited ~or use with natural and
synthetic rubber, particularly EPD~, other polymer composi-
tions ordinarily subjected to a moldiny operation can bemore conveniently used utilizing the mold release composi-
tion of the instant 1nvention. The mold release composition
of the invention is effective with synthetic rubbers such as
styrene-butadiene rubber, neoprene rubber, nitrile rubber,
polysul~ide rubber, and cis-1,4-isoprene rubbers. Various
molded polymers can also be produced using said mold release
compositions such as polyurethane polymers, polyesters,
polystyrene, polyamides and polyvinyl chloride.
The amount of the mold release composition
ernployed generally will depend on the particular use and the
particular poly~er with which the mold release composition
or lubricant of the invention is employed. Where the mold
release compositions of the invention are partially compat-
ible with the high rnolecular weight poly~er, i.e., the
elastomer, amounts ranging from about 1 percent up to about
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40 percent by weight of said polymer can be employedO
However, if the lubricant or mold release composition of the
invention is not compatible with said high molecular weight
polymer, amounts ranging from about 0~1 up to about 5 weight
percent of said polymer are employed.
In accordance with the instant inven~ion, the
copolymers of formulas I and II above, may be subjected to
filtration treatment. More specifically, upon completion of
the polymerization reaction the product is allowed to cool
to 80C and an absorbent such as magnesium silicate added to
the product at levels of 1 to 5 percent. This slurry is
stirred for 1 to 3 hours. It is then filtered to remove the
absorbent and catalyst used in the reaction.
The polyoxyethylene-polypropylene copolymer may be
neutralized with any conven~ional acid normally used for
this purpose. These acids include acetic acid, phosphoric
acid, hypophosphorous acid, ethylhexanoic acid, salicylic
acid/ citric acid, oxalic acid, sulfuric acid, benzoic acid
and hydrochloric acid.
The invention will be further illustrated by the
following specific exa~ples. Where not otherwise specified
throughout the specification and claims, temperatures are in
degrees centigrade and parts, percents and proportions are
by weight.
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In the examples:
Polymer #1 i5 a polyoxyethylerle-polyoxypropylene
block copolymer of the type shown in formula I, above,
having a molecular weight of the polyoxypropylene hydrophobe
of 3250 and containing 30 percent by weight oxyethylene
groups.
Polymer #2 is polyoxypropylene glycol having a
molecular weight of 410.
Polymer ~3 is a polyoxyethylene-polyoxypropylene
block copolymer of the type shown in Eormula I, above,
having a molecular weight of the polyoxypropylene hydrophobe
of 3250 and containing 50 percent by weight oxyethylene
groups.
Polymer #4 is polyoxyethylene glycol having a
molecular weight of 400.
Polymer #5 is a polymer of formula II, above,
wherein R is a linear alkyl group having 12 to 15 carbon
atoms, the total molecular weight is 820 and the percent of
oxyethylene groups is 25.
: 20 Polymer #6 is a heteric polyoxyethylene-polyoxy-
: propylene copolymer having a molecular weight of the
~: polyoxypropylene groups of 3250 and containing 50 percent by
weight oxyethylene groups~
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Examples 1-13
We~ting tests were performed on samples of uncured
EPDM elastomer applying the lubricant composition set forth
in Table I below to the surface of the elastomer and
observing the degree of wetting at room temperature. The
coated elastomer piece was then placed in a temperature
controlled oven at about a 45 angle and maintained in the
oven at the specified temperature, i.e., 45C and/or 75C,
for 30 minutes. The surface was then evaluated visually for
wetting after a 30 minutes waiting period. In Table I the
indication "complete" means that the lubricant composition
gave complete coverage of the surface at the indicated
temperature and did not contract to leave bare spots.
"Partial" means that some bare spots were observed r but that
the surface was still at least 50 percent covered by the
luhricant. "None" means that less than 50 percent of the
surface remained covered by the lubricant composition. The
results of these tests are indicated in Table I which
follow~.
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~1 dP dP g OP o~ O
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O + + + + + -~ ~ + + +
~1 ~1 ~ ~ _I ~1 ~I C~ O O
2 d~ d d~
1~! dP dP ~0 o~ dP o~ ~IP dO dP dP O O O
U u~ O Cr co Ir) O O O O
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Examples 14
A lubricant composition consisting of 99 percent
polymer No. 1 and 1 percent polymer No. 5 when employed
under actual hose molding conditions exhibits complete
wetting before and after vulcanization, and the molded
elastomer is characterized by a uniform non-cracking matte
appearance.
Example 15
A composition of 99 percent Polymer ~3 and
1 percent Polymer #5 was prepared wherein Polymer #3 was not
filtered but was neutralized with 0.11 percent acetic acid
(100 percent) based on the amount of the Polymer #3 and
; Polymer Wo. 5 was neutralized with 0.11 percent H3PO4 (100
percent acid) based on the amount of Polymer No. 5. This
composition was subjected to the wetting test set fGrth in
Examples 1-13 and the result was complete wetting at room
temperature and 45C with a matte finish having no haze
after 24 hours at 80C.
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